I think maybe the best place to see the lap dovetails if you ever want to study them is the region comprised of the Black Forest, parts of Bavaria, Switzerland (particularly the Canton of Bern, where archaic forms are best preserved) over into parts of Austria and into Hungary -for the most part, places of Alemannic settlement but which often happen to have distinct Gothic and Burgundian influences. The Hungarian framing, for example, can be said to be of Gothic descent to a large degree.
As for your joints, I think they are well fashioned, and I would not worry about refining them too much if they are going to be 'blind' that is covered and concealed -this is good practice to learn them really. And as for twisting or withdrawing, since they will be sheathed over this is really not a concern at all
